NATURE OF DEPOSIT OBTAINED FROM MILK. — 167 
when a little acetic acid was added to a suspension of the 
deposit in water. These facts indicate the presence of 
caseinogen or its compounds. Two direct estimations of 
caseinogen were carried out as follows:—The deposits were 
suspended in volumes of water equal to the volumes of milk 
from which they were obtained, and the caseinogen was 
precipitated by the addition of one drop of 33% acetic acid 
to each 10 cc. of the suspension. The precipitates obtained 
were separated from the superfluid in the centrifuge, and 
washed three times with a solution of acetic acid (1 drop 
of 33% acetic acid to 10 cc. of water). The precipitates 
were then collected on tared filters dried to constant 
weight in a glycerine oven at 103°, and weighed. The 
following are the results obtained :— 
Percentage of Caseinogen in Deposit. 
Deposit. |Weight of Deposit. ees yeas 
46 0:0779 gm. 0:0441 gm. 56°6 
48 OOS. «,. 0.05351 2 aS) 
The greater part of the nitrogenous material of the 
deposit therefore consists of caseinogen. The precipitates 
of caseinogen were found to contain 2% of ash. 
On subtracting the mean of these two percentages from 
the total percentage of protein in the deposit, as calculated 
from the total nitrogen-content it is seen that there is 
present in the deposit about 16% of protein not caseinogen. 
This nitrogenous matter is possibly derived from the 
general cellular débris from the epithelia of the different 
parts of the mammary gland of the cow. Such material . 
is always obtained in the deposit formed when milk is 
allowed to stand, even in the milk from perfectly healthy 
cows (Ernst, 1913). A microscopic examination of the 
deposits obtained from milk in the present case showed 
